JPH0696730A - Optical metal halide lamp device - Google Patents

Abstract

PURPOSE:To raise the illuminance ratio on the screen to prevent the unevenness of illuminance and color, and improve the average illuminance and the illuminance maintenance factor by forming the surface of an upper part of a light emitting tube, which is divided into an upper part and a lower part by a horizontal axis between both electrodes, into a frosting part, and forming the surface of the lower part into a clear surface. CONSTITUTION:The light emitted from a clear part of a light emitting tube 1 goes out straight from the surface of a lamp without scattering, and it is reflected by a reflecting mirror 9 and projected toward a part a little upper than the center of a screen to raise the illuminance of this part. On the other hand, among the light emitted toward a frosting part 6, about 1/2 of the light passes the frosting part 6 and goes out straight and it is projected to a part a little separated from the center of the screen. The light scattered in the frosting part 6 is projected to an area lower than the center of the screen or the peripheral area thereof. Consequently, a screen, of which upper side is a little brighter than the center thereof and which has a large average illuminance and a large illuminance ratio, can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical metal halide lamp device, and more particularly to an improvement of a metal halide lamp used as a light source for a relatively small-sized optical image device which is combined with an optical mirror to distribute light in an optically limited area. .

[0002]

2. Description of the Related Art Conventionally, a small-sized metal halide lamp device, which is constructed by integrally or detachably combining an arc tube and a reflecting mirror without using an outer tube, has a good color rendering property and a high luminous efficiency. Due to such features, it is being used as a light source for overhead projectors, overhead type liquid crystal projectors, liquid crystal projection televisions, and projectors. The metal halide lamps used for these are almost spherical arc tubes.
Besides merging mercury and argon as a start-up assisting gas to a predetermined lamp voltage, dysprosium iodide and neodymium iodide are contained in predetermined amounts. The lamp (light emitting tube) thus constructed without using the outer tube is composed of hard glass with wires at both ends connected to the lead wire and the base, and is surrounded by a cold mirror film on the inner surface. The metal halide lamp device is configured by mounting the reflecting mirror provided so that its central axis substantially coincides with the axis of the arc tube and leading one end of the lead wire to the outside of the reflecting mirror and connecting it to a terminal. The metal halide lamp device configured as described above is used as a light source for a liquid crystal projector or the like.

[0003]

However, the metal halide lamp device used for the above-mentioned optical device has the following problems. Assuming that the light emitting part of the arc of the arc tube is located at the center of the arc tube, the light emitted from the light emitting part toward the clear surface passes almost linearly without being scattered by the clear surface. Therefore, when projected on a screen having an aspect ratio of 3: 4 as shown in FIG. 3 through a lens system, the straight-ahead light emitted from the metal halide lamp through the clear surface is reflected by a reflector portion near the lamp. It is reflected and reaches the screen through the lens system.

The straight traveling light passing through this clear surface is hardly scattered and becomes a considerable amount, and the straight traveling light emitted to a portion of the reflecting mirror near the arc tube is reflected because the eccentricity is small. When the illuminance distribution along the line AA ′ of the screen is measured, the illuminance near the center is extremely high but the peripheral illuminance is significantly low, as indicated by the curve a in FIG. Then, the illuminance ratio related to the illuminance measured at the measurement point at the center of the area obtained by dividing the screen into nine equal parts is represented by the mathematical formula 1.

[0005]

[Equation 1]

When a metal halide lamp having most of the arc tube as a clear surface is used as in the prior art, the illuminance ratio is as low as about 10%. However, it is empirically said that the illuminance ratio of 30% or more is visually preferable, and in the case of using the metal halide lamp having the clear surface as described above, the illuminance unevenness on the screen occurs due to the low illuminance ratio. There is a problem that it becomes extremely uncomfortable.

Therefore, in order to eliminate the discomfort caused by the uneven illuminance, it is possible to form a frosted portion over the entire surface of the arc tube. The frosted portion can be obtained by pear-treating the outer surface of the arc tube by a so-called sandblasting method in which glass beads are jetted onto the clear outer surface of the arc tube using high pressure gas. In the arc tube having the frosted portion obtained in this way, as shown in FIG. 5, about half of the light 25 emitted from the light emitting portion at the center of the arc tube 21 is straight ahead light 26 in the frosted portion 22.
And the rest of the light is scattered as light 27
Is emitted from the frost portion 22.

Therefore, when the arc tube having the frosted portion 22 formed on the entire surface of the arc tube 21 excluding the heat insulating film 23 is arranged in the reflecting mirror and irradiated on the screen, the emitted light has a relatively large eccentricity. About 1/2 of the straight light hits the reflecting mirror portion and is reflected, and reaches the periphery of the center of the screen. Further, the scattered light reaches the central portion and the peripheral portion of the screen, respectively, though only a small amount, and when the illuminance distribution along the line AA ′ on the screen is measured,
In, the curve b is shown by a dotted line. As can be seen from this measured illuminance, the illuminance ratio can be increased, but the overall illuminance decreases, and the desired illuminance cannot be obtained even in the central part, and the light quantity is scattered too much and wasted. There is a problem that it is closed.

The present invention has been made in view of the above, and it is possible to raise the illuminance ratio on the optical screen to eliminate the illuminance unevenness and the color unevenness, and to improve the average illuminance on the screen to obtain a clear image. The present invention provides an optical metal halide lamp device having excellent life characteristics.

[0010]

According to the present invention, a reflecting mirror having a reflecting surface such as a parabolic surface or an elliptic surface and an axis connecting the two electrodes of the arc tube are substantially aligned with the central axis of the reflecting mirror. In the metal halide lamp device for optics, which comprises a metal halide lamp arranged on the front surface of the reflecting mirror without using an outer tube, the metal halide lamp forms a frosted portion only on the outer surface of the arc tube in the horizontal lighting posture, The lower part of the surface is characterized by a clear surface. or,
If necessary, a reflection and heat retaining film formed on the outer surface of the arc tube around the electrode located on the opening side of the reflecting mirror, and from the edge of the heat retaining film, the upper hemisphere of the arc tube with a horizontal axis between the electrodes. A frosted portion is formed on the surface and the lower hemispherical surface is a clear surface.

[0011]

In this way, when the screen is irradiated by arranging the frosted portion not on the entire outer surface of the lamp but on the upper hemispherical surface of the arc tube with the horizontal axis between the two electrodes, especially from the edge of the reflection and heat insulating film. As a result, it is possible to obtain a desired illuminance in the central portion while reducing a decrease in the overall illuminance. Therefore, it is possible to obtain a clear image by setting the illuminance ratio to 30% or more to reduce the illuminance unevenness and improving the average illuminance of the screen.

[0012]

EXAMPLES Examples according to the present invention will be described below with reference to FIGS.
It will be explained based on. FIG. 1 is a side view of a metal halide lamp, and FIG. 2 is a partially cutaway side view of an optical metal halide lamp device. In the figure, 1 is the maximum outer diameter 11 mm,
An arc tube with a substantially circular cross section, consisting of a quartz container with a maximum inner diameter of 8.8 mm and an internal volume of 0.4 cc.
A and 2b are provided so that the distance between the electrodes is 5 mm.
The electrodes 2a and 2b have a diameter of 0.45 mm and a length of 6.5 mm Th.
A tightly wound coil, in which a tungsten wire having a diameter of 0.32 mm is wound around a coil length of 2.5 mm, is arranged on an O ₂ -containing tungsten core rod, and the coil is arranged 0.5 mm away from the tip of the core rod. Also, edged foils 3a and 3b made of molybdenum and having a width of 1.5 mm and a length of 12 mm, which are welded to the electrodes 2a and 2b, are provided to maintain airtightness with the arc tube 1, and have a diameter on the extension thereof. Wire 4a made of 0.6 mm molybdenum wire,
4b is provided and electric power is supplied from the outside. In the arc tube 1, 0.5 mg of dysprosium iodide, neodymium iodide and cesium iodide selected at a weight ratio of 4: 2: 3 in addition to mercury and argon, is enclosed.

On the outer surface of the lamp of the arc tube 1 corresponding to the peripheral portion of the electrode 2b located on the opening side 9a of the reflecting mirror 9 which will be described later, light composed of, for example, an Al ₂ O ₃ --SiO ₂ mixture is used. A reflective and heat-resistant reflective and heat insulating film 5 is formed by coating. Further, frosting is performed from the edge 5a of the heat insulating film 5 to both upper electrodes of the arc tube with the electrodes between the electrodes 2a and 2b as a horizontal axis to form a frosted portion 6.

As shown in FIG. 2, the arc tube 1 thus constructed has its wires 4a and 4b connected to a nickel lead wire 7 and a base 8, respectively, so as to surround the arc tube 1 and to have an inner surface. A reflecting mirror 9 made of hard glass with a cold mirror film and having a diameter of 100 mm and f = 13 is attached so that its central axis substantially coincides with the axis of the arc tube 1, and one end of the lead wire 7 is attached to the reflecting mirror 9. Lead out to the terminal 10
To form a metal halide lamp device.

When the metal halide lamp device thus constructed is lit at a rated power of 150 W using a rectangular wave of about 270 Hz, the total luminous flux is 12000 lm and the color rendering index Ra8.
5. Emitting characteristics of color temperature 7,000K, luminous efficiency 88
It is lm / W, and has excellent characteristics as an image light source. Then, when projected on the screen shown in FIG. 3 with a predetermined optical system, an average illuminance of 5000 lx was obtained. Similarly, when the illuminance distribution was measured along the line AA ′ of the screen, the illuminance characteristic as shown by the chain line in FIG. 4 was obtained, and the illuminance ratio was 35%, and illuminance unevenness and color unevenness were generated. There wasn't.

The reason why the high average illuminance and the appropriate illuminance ratio are obtained as described above is considered to be as follows. As shown in FIGS. 1 and 2, in the metal halide lamp of this embodiment, the light emitted from the clear portion 1a is emitted straight from the surface of the lamp without being scattered, is reflected by the reflecting mirror 9, and is centered on the screen. It is projected slightly above the section. The light passing through the clear portion 1a is emitted straight without being scattered as described above, so that the illuminance is slightly higher than the central portion on the screen.

On the other hand, the light emitted toward the frosted portion 6 passes through the frosted portion 6 as it is, and the light emitted straightly is approximately 1/2, and is projected on a portion slightly apart from the central portion of the screen. To be done. The light scattered by the frosted portion 6 is projected to a portion slightly below the central portion or the peripheral portion of the screen. Therefore, it is possible to obtain an excellent screen in which the screen shown in FIG. 3 is slightly brighter than the central position and has a large average illuminance and illuminance ratio. or,
In the lighting test, as shown in FIG. 6, the illuminance maintenance ratio of the device according to the present invention is better than the conventional one, and the maintenance ratio after lighting for 2000 hours is increased by about 15%.

[0018]

As described above, the optical metal halide lamp device according to the present invention can increase the illuminance ratio on the screen required for the optical device to 30% or more with a relatively simple structure. Also, it is possible to eliminate color unevenness, obtain a clear image by improving the average illuminance, and obtain a device having excellent lamp life characteristics.

[Brief description of drawings]

FIG. 1 is a side view of a metal halide lamp according to the present invention.

FIG. 2 is a partially cutaway side view of the same metal halide lamp device.

FIG. 3 is an explanatory diagram showing a screen used for measuring average illuminance and illuminance ratio.

FIG. 4 is a characteristic diagram showing an illuminance distribution of the device along the line AA ′ of the screen shown in FIG.

FIG. 5 is an explanatory diagram showing a light emission mode in a conventional metal halide lamp.

FIG. 6 is a characteristic diagram showing a change in illuminance maintenance rate with the passage of a lamp lighting time.

[Explanation of symbols]

 1 Arc tube 1a Clear surface 2a Electrode 2b Electrode 3a Edged foil 3b Edged foil 4a Wire 4b Wire 5 Reflective and heat-retaining film 6 Frost part 7 Lead wire 8 Base 9 Reflector 10 Terminal

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[Procedure amendment]

[Submission date] September 24, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 3]

[Figure 4]

[Figure 5]

[Figure 6]

Claims (2)

[Claims] 1. A reflecting mirror having a reflecting surface such as a parabolic surface or an elliptic surface and an axis connecting the both electrodes of the arc tube are arranged on the front surface of the reflecting mirror so as to substantially coincide with the central axis of the reflecting mirror. In a metal halide lamp device comprising a metal halide lamp that does not use an outer bulb, in the horizontal lighting posture, the metal halide lamp is an optical metal halide in which only the upper portion of the outer surface of the arc tube forms a frosted portion and the lower portion of the outer surface of the arc tube serves as a clear surface. Lamp device. 2. The metal halide lamp includes a reflection and heat retaining film formed on an outer surface of an arc tube in a peripheral portion of an electrode located on the opening side of the reflecting mirror, and a horizontal distance between both electrodes from an edge of the heat retaining film. The optical metal halide lamp device according to claim 1, wherein a frosted portion is formed on the upper hemispherical surface of the arc tube as an axis, and the lower hemispherical surface is a clear surface.